Annular Pressure Responsive (APR)

Definition - What does Annular Pressure Responsive (APR) mean?

An Annular Pressure Responsive is a downhole tool that bypasses the differential pressure buildup caused by hydrocarbons in the annulus. It consists of a hydraulic bypass which is helpful in bypassing of the pressure between two strings
of casing inside a producing well. The tool also has a power piston
that can subsequently move to change the annulus pressure in the well. This piston remains at a particular position so that annulus pressure can be
maintained.

Petropedia explains Annular Pressure Responsive (APR)

Annular pressure buildup in well is a common thing during the lifetime operations of a producing well. Because of annular pressure, a well may experience different pressure and temperature, mechanical shocks, etc. Sometimes, such experiences are also acknowledged because of various ongoing nearby drilling or pressure buildups in the reservoir formation. Such pressure needs to be handled in order to avoid any workover operations.

The annular pressure responsive tool helps operators in managing the annulus pressure buildup in the well. This tool consists of various tools such as Power piston whose position can be hydraulically adjusted by the means of an actuator.